WhiteWhite Paper:Paper: AmbientAmbient Air’sAir’s ImpactImpact onon CompressedCompressed AirAir SystemSystem PerformancePerformance

Most stationary industrial air and dryers are located indoors — inside a factory in a “ room.” It’s also common to see them along a wall or tucked into a corner of the factory floor where production is taking place. Proper ventilation and ducting of the “compressor room” is required to maintain inlet air temperatures within design specifications. Compressor room ventilation also provides significant heat recovery opportunities when properly managed. The Hitachi DSP Next Series of Oil-Free Air Compressors Ambient air can carry contaminants able to negatively impact the compressed air equipment and the Ambient Air’s Impact on quality of the compressed air. They can reduce compressed air system Compressed Air System equipment durability and life and also create production disruptions Performance by impacting production equipment or creating product rejects. By Nitin G. Shanbhag, Senior Manager, Air Technology Group, Hitachi America

I. Managing Inlet Air Introduction Temperature” when referring to and Temperature To Air air compressors. Decreases in inlet Compressors and Dryers Ambient air conditions have a pressure reduce an air compressors Compressed air is often described significant impact on rotary screw ability to produce compressed air. as “dynamic” — meaning that the and refrigerated air The two most common causes operating characteristics, such as dryer performance. Understanding of reduced inlet pressure are higher input energy required for specific and managing equipment inlet air elevation and restrictive inlet piping work, is ever-changing. These pressure and temperature, ensuring or filtration. Increases in ambient changes in operating characteristics proper compressor room ventilation, air temperature reduce the efficiency are caused by many factors including and managing airborne particulates, of air compressors and air dryers. cooling water temperature, electrical caustic gases and oil mists, will have Managing ambient pressure and drive train issues, capacity controls, a direct impact on the reliability and temperature helps end users ensure storage, etc. The most overlooked quality of a compressed air system. their compressed air systems can factor, however, is the most significant Ambient air pressure and temperature efficiently deliver the expected volumes one — changes in the ambient air is also known as “Inlet Pressure and and purity of compressed air. surrounding the air compressor.

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Lower Inlet Air Pressure: • A fixed inlet volume of air at a Actual Cubic Feet per Minute and The Effect of Elevation higher ambient pressure weighs represents the actual volume of on Air Compressors more than the same volume at ambient air that is taken in by the air a lower ambient pressure The ambient condition of inlet air to the compressor and delivered to the air air compressor affects the net weight • Water vapor in the inlet air is system at final discharge pressure. of the final delivered compressed compressed, discharged and Some companies use the term FAD air to the system. Specifically, inlet removed by the compressed (free air delivery) instead. This air temperature, pressure and relative air drying system and represents is taken at whatever temperature, a reduction in the weight of air affect both the density and pressure, and relative humidity that compressed and delivered to weight of the total compressed air exists at the inlet of the air compressor. the system ultimately delivered to the compressed This means at inlet conditions, air users in the plant. Keep in mind Understanding Air Flow Terms: production machine and flow meter the following: ACFM, SCFM and FAD manufacturers convert ACFM or FAD • A fixed inlet volume of cold Most rotary screw manufacturers into SCFM to correct the flow rate air weighs more than the same describe the volume of air flow their to a standard set of conditions. This volume of warm air equipment can provide in terms of corrects (usually lowers) the usable ACFM and FAD. ACFM stands for volume to allow for ambient changes

Figure 1: Inlet Piping Restrictions at a Foundry Reduce Inlet Air Pressure

2 in pressure, temperature and relative 550 ºR) and 90% relative humidity. inside the production machine in humidity. SCFM is calculated on the The calculation reduces Denver’s net the example. standard set of inlet conditions of 14.5 inlet ambient pressure to 12.2 psia psia (1 Bar) ambient inlet pressure, 68 ºF minus .4882 psia, which is the effect Example #2: This example comes (460+68=528 ºR) ambient temperature, of removing the water vapor with the from a compressed air audit at a pet- and 0% relative humidity. dryer before it goes to the system. This food plant, located at a high elevation, establishes a net inlet pressure of 11.71 in Northern Arizona. The plant had a The Effect of Altitude psia, not including inlet filter losses. retort filling process causing significant on Sizing Air Compressors — problems. Retort is a filling process Two Examples Acfm = 900 scfm x where the product is poured into a container, and then cooked and Example #1: A production machine 14.5 psia 550 ºR x sterilized inside the container. requires 900 scfm of compressed 11.71 psia 528 ºR air to function properly. The plant is = 1161 acfm When the air compressor and retort located in Denver, Colorado, where process was installed at the plant average ambient air pressure is 12.2 At this elevation, the production site, the actual fill time was 11.5 to psia. The plant manager understands machine needs about 23% more 12 minutes. The maximum allowable they cannot assume a “900 scfm” inlet compressed air (1161 acfm refill rate was 9.5 minutes. This refill air compressor will provide enough versus 900 scfm) to deliver a similar rate surprised the plant engineers air. Also assumed is an ambient density or weight of compressed who had selected the 350 hp, two- temperature of 90 ºF (460 + 90 = air to run the pneumatic process

Table A: The Approximate Impact of Altitude on Rotary Screw Air Compressors

Nominal Approx. Approx % Atmospheric Delivered Delivered Altitude Pressure Compression Capacity Capacity Feet psia/Bar Ratio acfm/M3 min scfm Bhp As the altitude increases, 0 14.70 / 1 7.80 1000 / 92.9 100.0 187 1. The actual capacity at intake decreases only 2000 13.66 / .94 8.32 995 / 92.4 93.5 179 slightly

2. The scfm delivered to 4000 12.68 / .87 8.89 990 / 92.0 87.1 171 the system decreases materially

6000 11.77 / .81 9.50 985 / 91.5 81.2 163 3. The bhp decreases materially. 8000 10.91 / .75 10.15 980 / 91.0 75.4 156

10000 10.10 / .69 10.90 975 / 90.5 69.8 149

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stage, lubricant-cooled, rotary screw Manage Man-Made Causes the more a unit volume (of air) will compressor and retort combination of Low Inlet Pressure weigh, thereby producing greater — planning a refill rate of 8.5 minutes. Most of the time, low inlet pressure scfm. In oil-free rotary screw air A slower refill rate was unacceptable is caused by man and not by mother compressors, the actual swept volume and had a negative impact on nature. The most common causes of inlet air has more effect on power production. So what happened when of low inlet pressure are avoidable draw than does the scfm or weight of sizing the air compressor? — created by issues with installations air. As the ambient temperature falls, and maintenance. Very common issues delivered air scfm increases at a much The answer was the impact of include restrictive inlet piping, dirty greater rate than the power. The net higher elevation. Due to elevation, inlet filters, and out of adjustment inlet result leads to a relatively accurate the air compressor was provided valves. These immediately have the guideline — every 5 ºF of cooling with an actual 11 psia inlet pressure same effect, as higher elevation, in leads to a 1% improvement in specific instead of the standard 14.5 psia reducing the inlet pressure to the air power or efficiency (scfm/input kW). inlet pressure used when selecting compressor. the air compressor. When sizing the Air-cooled air compressors and air compressor, the refill rate was Example: A compressed air audit, accessories (particularly after coolers) established at 1820 acfm at 14.5 psia at a foundry, discovered 300 feet of are used throughout the world. Their ambient pressure, needing 8.5 minutes 6” pipe feeding inlet air to three 150 performance is directly tied to the to increase pressure from 0 psig to horsepower, lubricant-cooled, rotary ambient air temperature and pressure. 80 psig with a 350 hp rotary screw screw air compressors (see Figure 1). As ambient pressure falls, the ability compressor. Instead, the result at 11 The inlet piping was very restrictive of the cooling air to transfer heat also psia inlet pressure, was 1293 scfm and reduced inlet pressure from the falls as the air is now at a lower density. at 100 psig, requiring 385 bhp (405 expected 14.2 psia to 9.5 psia. The When both ambient temperatures are input hp), and unacceptable refill rates impact of this lower inlet pressure higher and ambient are lower of over 11.5 minutes (adding two was a reduction in available working — performance issues become even minutes per fill). compressed air from the projected more significant. 2,175 scfm to 1,503 scfm. The foundry The lower inlet pressure of 11 psia Lubricant-cooled rotary screw or vane needed more compressed air and caused a 25% reduction in the weight compressors inject lubricant (at 150 ºF couldn’t understand why the air of air and the extra energy required to 160 ºF) into the compressed air, compressor couldn’t supply enough. to perform the same function was 405 either at the inlet or immediately after input horsepower for 2 minutes longer In summary, after the compressor is seal-off. The oil acts as a coolant per cycle. This resulted in a $79,400/ selected to deliver the proper scfm and absorbs most of the heat of year unanticipated electric energy at site conditions, care must be compression. Regardless of design, operating cost at $.10/kWh. exercised to not take any actions in some of this hot coolant/lubricant installation or maintenance that would finds its way back to the inlet, where In summary, the lighter the air going lower the inlet pressure and render it can have a significant effect on into an air compressor, the more the compressors too small. the temperature of the air entering ambient air needed to do the same the rotary compression element(s). work — such as run an air motor, fill The Impact of Ambient Air This localized heating of the inlet air a volume tank, run air cylinders, etc. Temperature on After-coolers basically offsets any gain in cooler inlet The higher elevation brings lighter air under normal operating conditions. into the air compressor and higher As ambient air temperature increases, temperature brings lighter air into the air’s density is reduced. As Since the ambient air supplies the the compressor. ambient air temperature is reduced, cooling air to the aftercooler, the

4 ambient temperature is very critical. packages are offered to increase the the temperature rises the amount At lower ambient pressures, the maximum ambient temperatures. of vapor to be condensed per cubic effective cooling or exchange of heat is foot increases — requiring more reduced further, thus directly reducing The Impact of Inlet Air capacity to maintain performance. This leads to evaluating Temperature and Pressure on the required pressure dewpoint. these situations on a site specific basis. Refrigerated Air Dryer Sizing Note that as the inlet temperature The correction chart (Table B), used rises from 100 ºF to 120 ºF at 100 Most air-cooled aftercoolers have a to size refrigerated dryers, shows psig, the saturated flow rating must ΔT rating of 10 ºF to 50 ºF - with larger the effects of inlet temperature and be reduced about 32% (.68 multiplier). industrial units usually being 15 ºF. pressure on the flow rating of a This means that the maximum cooling Most standard refrigerated dryers refrigerated dryer. Dryer flow ratings air temperature to the air-cooled heat can operate under maximum ambient are based on the total amount of exchanger should be about 85 ºF with temperatures of 110 ºF and maximum water vapor that can be held in vapor a 10 ºF ΔT. inlet temperatures of 120 ºF. form for the scfm flow at 100 ºF inlet and ambient temperatures. At colder Extremely high ambient temperatures In North America, refrigerated air dryers temperatures, the refrigeration capacity can shut-down air compressors. Most have their flow ratings established by can handle higher flows (although standard rotary screw compressor using the “three 100’s.” This is practical excessive pressure loss may be an packages will have a “not to exceed” only for remembering because it’s not issue). Hotter air holds more water maximum ambient temperatures of probable to see 100 ºF ambient with vapor in vapor form, therefore, as 104 ºF to 115 ºF. Special cooling 100 ºF inlet temperatures to a dryer.

Table B: Refrigerated Air Dryer Correction Factors for Inlet Air Pressure and Temperature

Inlet Air Pressure Inlet Air Temperature psig Bar 90 ºF 100 ºF 110 ºF 120 ºF 130 ºF

30 3.0 0.92 0.71 0.56 0.44 0.35

50 4.4 1.07 0.83 0.66 0.54 0.44

80 6.5 1.19 0.95 0.77 0.63 0.52

100 7.9 1.25 1.00 0.82 0.68 0.56

125 9.6 1.31 1.05 0.86 0.72 0.61

150 11.3 1.34 1.08 0.90 0.75 0.64

175 13.0 1.37 1.11 0.92 0.78 0.66

200 14.8 1.39 1.14 0.95 0.80 0.68

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In Europe, ISO standard flow rating Example: Figure 2 shows what II. Proper Ventilation to conditions are a bit more practical occurs when refrigerated air dryers Remove Heat from the setting standard ambient temperature are sized with unrealistic dryer Compressor Room(s) at 77 ºF, inlet temperature at 95 ºF, and inlet temperatures. As the ambient pressure at 103 psig (7 bar). temperatures climb and the air cooled Often the actual operating ambient after-coolers become less efficient, conditions are dictated by the ventilation the dryer inlet climbs from 100 ºF to (or lack there-of) in the compressor Standard Conditions for room(s) in the plant. The serious Refrigerated Dryer Flow Ratings 120 ºF or higher and, in this example, for a 38 ºF Pressure Dewpoint the pressure dewpoint rises from issues created by poor ventilation can North 40 ºF to +77 ºF — basically delivering include negative pressure (low ambient America Europe wet air to the plant air system. It is pressure), high ambient temperatures, Ambient 100 ºF 25 ºC not uncommon to see refrigerated and the high potential for compressor Temp. (38 ºC) (77 ºF) dryers experiencing 130 ºF inlet air inlet contamination. These issues are 100 ºF 35 ºC not site-created (like elevation), they Inlet Temp. temperatures. This why one often (38 ºC) (95 ºF) hears, “the dryer works ok except are man-made and can always be Inlet 100 psig 7 bar in hot weather!” eliminated. Their negative impact is Pressure (7.9 bar) (103 psig) significant with regards to the energy

Figure 2: Focus on Ambient and Inlet Temperatures When Sizing Refrigerated Dryers

6 cost, performance and reliability of the cases, it is suggested the plant utilize compressed air system. the services of a professional HVAC Cfm 585,580 engineer. However, to get a general cooling = 54,220 cfm air = 10.8 Figures 3 and 4 show two of the idea of what is required to ventilate the most common forms of compressor compressor room (without refrigerated room ventilation. These and variants air conditioning) to a certain degree The cooling fan of a typical 200 hp of these will all work. The first step level above the surrounding ambient lubricant-cooled, rotary compressor is — what is the total heat load in the temperature, use the following: will probably move about 20,000 cfm compressor room? (565.23 M3) of cooling air out, leaving Cfm cooling air required to ventilate a an additional high potential required • Compressor drive motor room and hold a 10 ºF level above the cooling air flow of about 35,000 cfm. • Fan motor/pump motor surrounding ambient air temperature. • Dryer heater This is based on a full exchange of air. There are variables that may drive this answer somewhat lower (or higher). • Blower motor Typical commercial 200 hp class air The main point is when an air-cooled, • Refrigeration drive motors cooled, lubricant-cooled rotary screw: lubricant-cooled, rotary screw uses • Variable speed drives ductwork to take the cooling air out • Other operating equipment of the room, an additional room air Cfm (sensible heat) (btu/hr) cooling exchanger will be required. Water- Total horsepower times 2546 btu/hour air = 1.08 (T1-T2 temperature rise) cooled units will generally reject less will provide an approximate estimated heat to the room than air-cooled. btu/hr heat load. Do not use Bhp Cfm (230 hp) 2546 btu/hr (compressor shaft) motor nameplate, cooling get actual input horsepower. In most air = 1.08 x 10

Control Compressor Room Temperatures to between 40 ˚F (min) and 100 ˚F (max)

Figure 3: Side-Wall Inlet and Side-Wall Outlet Ventilation Figure 4: Roof Inlet and Roof Outlet Ventilation and Make-up Air Flow and Make-up Air Flow

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ducting, similar to Figure 3, where Airborne Particle Contamination heated cooling air was dumped back Airborne particle contamination into the compressor room to keep it is usually a very straightforward warm with thermostatically controlled contaminant that is often ignored. louvers and the improper ducting was The compressor OEM installs an inlet reconfigured. Proper make-up air was air filter usually rated for “standard allowed back in and the operating conditions” which most often means ambient pressure returned to 14.2 99% removal of all particulate 5 micron psia. The 60 hp air compressor was no and larger and 95% removal of all longer needed, the six months a year particulate 3 micron and larger. Figure 5: Monitor Outlet Cooling Air Temperatures of cold weather (4350 hours/year) and for Flow Restrictions the electric power energy savings was Normal life of these elements is (51 kW)($.11/kWh) x 4350 hours/year expected to be two months to six Figure 5 shows improper ducting. = $24,400/year. The total project cost months. When high dust applications Note the ducting on the 200 hp air was $12,800. are encountered (such as at corrugator compressor was restricting the flow of plants, mineral processing), the high- In summary, wherever the compressors the cooling air out causing a 9 ºF rise in dust levels will usually be quite visible are operating, the plant operations inlet temperature over the 95 ºF room and a high-dust version of the inlet filter personnel should be aware of the temperature. The room temperature is used which normally includes a pre- actual operating ambient conditions. was 95 ºF when the outside ambient cleaning area where the heavier dust Are they optimum? Remember, in order temperature was 45 ºF (ΔT 50 ºF) and loads fall out and are removed before to measure psia, a vacuum gauge three walls of the room were outside. they get to the main filter element. is needed. There were two 200 hp compressors Example: The major (and not so with similar installation and one smaller obvious) problem with compressor 60 hp trim unit recently added that was III. Compressor Inlet-Air inlet air is not the visible high dust but ducted correctly. Contaminants; Solid Particles, Aggressive Vapors/Gases, when the inlet air ambient area has In order to hold the room temperature and Oil Mists very small fines (<3 microns smaller) higher, very little make-up air was which pass through the standard filters. As production machinery and brought into the room. The net result A good example of this was a plant processes continue to evolve, more was a significantly negative pressure manufacturing automotive catalytic and more industries are requiring of 12.2 psia when the outside ambient converters. The process filled the cleaner and drier air for both pressure was 14.3 psia. Basically, ambient area with a high concentration machinery reliability and product the room now seemed to be located of very small fines. These fines passed integrity. As line-speeds and in Denver, Colorado. This resulted in through the inlet filter and shortened productivity continue to accelerate, an approximately 14% reduction in the normal 1-2 year separator life (of a anything that stops production or available compressed air. lubricated rotary screw air compressor) significantly slows it down can have to two months. The first attempt to fix very expensive after-effects. Product In this example, the plant was running this was an oil bath filter which didn’t contamination can lead to expensive all three compressor units 24 hours a do a good job because it only wetted scrap levels, and even worse, brand- day. Modifications were made to the the screen properly at high flows — the damaging product recalls.

8 compressor was at modulation control Aggressive Caustic or Acidic appears to be very spacious in a with constantly varying flows, and at Vapor That May Become crowded plant. Often it becomes a low loads everything passed through Aggressive Once Inside storeroom for various plant supplies. even worse — resulting in as low as the Compressor It is not unusual to see such items as a one-month separator life. Aggressive airborne vapors and gases water cooler cleaners (usually acid), are often overlooked and hard to find. and water treatment supplies stored The final fix was a high quality, Depending upon the situation, they in or near the compressor and dryer oversized dry filter with an oil wetted can do very expensive damage. Some ambient air. pre-filter screen. The screen was kept of the more well-known aggressive oil wetted by a pneumatically aspirated Example: A soft drink syrup plant was vapor contaminants (such as flourides oil spray. It was effective in trapping the experiencing a great deal of problems and chlorides) are usually avoided fines and had to be manually cleaned with the extremely short life of the food by location as well as such items as about once a week. With this, the grade lubricant coolant (PAO) of the air cleaning acids, caustics, etc. However, separator problem went away. compressor. It was found that water in many cases the compressor room, treatment chemicals were being stored particularly when well-designed, Apart from the obvious damage with open containers right next to the particulates can do when introduced inside an air compressor, there is the outside fouling or plugging of all air-cooled heat exchangers such as oil/coolant air coolers, air-cooled aftercoolers, electric motor-cooling, and air-cooled condensers on refrigerated air dryers. Many air compressor units are packaged in full sound and ambient controlled enclosures. When this is the case, all incoming cooling air and inlet air to the compressor can be pre-filtered with material and methods appropriate to the identified contaminants before they enters the compressor package (see Figure 8).

The same panel type or air handling room filtration can be applied to total compressor room pre-filtration much as seen now in many laboratory and even powder paint installations. The simplest action of all is to identify the source of the contaminant and either eliminate or move the source, or move the location or area, from the inlet and cooling air source.

OSP 37 kW Next Series

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Evaluating a compressed air system ambient location is very critical to energy efficient operation and operating reliability. This topic is also something that maintenance personnel should address to be ensure continuous awareness.

Airborne Oil Mist Contamination Airborne oil mist contamination is another contaminant often overlooked. If the negative impact on the product integrity and/or operating equipment, particularly air cooled coolers, shows up early it can create a lot of problems unless identified and corrected.

Remember that the contaminant vapor or gas comes in with the air at a certain concentration. As the inlet air and contaminant vapor is compressed to a smaller volume, the concentration of the contaminant is increased. Hydrocarbons entering through the 75 kW Air-cooled Rotary Screw Air Compressor Cooling Air Flow compressor inlets and migrating through to product contamination compressor. After further investigation, compressor. Sulfur dioxide (SO2) is it was determined this to be the basic a very common transient vapor or (food, paint, etc) can come from many cause and the plant was warned that gas in many plants. The most common sources including: there would be an excellent chance sources are wash stations and battery • An outside plant wall on a that further damage would be incurred changers. If this gas or vapor enters parking lot or roadway with to critical internal parts of the air the air compressor where it becomes constant automotive exhaust compressor. concentrated along with the always

present water vapor (H2O), it can and • Operating forklifts in the area Plant personnel did not agree until it where the exhaust is often does combine into H2SO4 — was pointed out, that all copper pipe sulfuric acid — which then attacks taken into the compressor was now green from exposure to the internal parts of the compressor • Furnace or other similar ambient air. Once the chemicals were such as the aftercooler, drains, dryer, exhaust flue air migrating to removed, the problem disappeared. etc and particularly black iron pipe. the compressor area ambient This is a common enough problem Plants must also look out for benign that it bears special attention on Obviously this list could go on and vapors that can easily become a continuing basis. on, but what is to be done if you can’t aggressive once inside the air

10 avoid or eliminate the oil mist after the designed to adsorb the identified vapor of risk, you may want to change filters source is identified? contaminants after the compressed air on a predetermined regular basis or dryer and primary filters — problem install a trace measurement system The quickest and most practical way solved. Depending on the magnitude downstream to alert. Most if not all is to install an appropriate carbon filter,

Patented Closed-Loop Gear Case Oil-Mist Removal System A patented process exists to eliminate the risk of air One to three cfm of compressed air is regulated through compressor sump oil mist being reintrained by the a venturi. The venturi pulls a vacuum on the gearcase and compressor intake. Hitachi oil-free rotary screw air pulls the oil mist into a coalescing filter. The oil is removed compressors do not vent oil mist to atmosphere. This from the bottom of the housing, by a float trap, and patented process creates a closed-loop gear case oil returned to the gear case. mist removal system that recycles the oil to the gear case.

The Hitachi Patented Closed-Cycle Oil Mist Removal System – U.S. P 05011388.

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If the oil mist is allowed to become In reality, there are two ambients a viable part of the ambient air it will to consider: enter the compressor through the • Nature — the elevation and inlet, become concentrated and go general atmospheric condition. through the compressors, which, in The plant has no control of an oil free compressor there is no oil elevation and outside ambient separation system — and then enter temperature. These conditions the air system in varying levels of are truly dynamic and changing contamination. This could overwhelm on a continual basis. Plant a dryer filter system originally designed personnel have to understand Figure 9: Air cylinders, air tools, air motors, and for oil free discharge air. them and their impact on exhaust air are a common source of oil mist and solid particulate contaminants equipment performance A new closed loop, gear case, oil mist and efficiency and operate recovery system has been introduced of these type of filters will not have a accordingly. to the market, in an oil-free screw physical signal (like measurable change compressor, to address and eliminate • The internal plant operating is ΔP pressure loss) when the filter this issue (see diagram on page 11). ambient conditions can be very is saturated. hostile. In fact, more hostile • 99.99% of the oil mist is Many oil mist ambient contamination than nature. These conditions reported to be removed from problems are easy to observe and were created by people and in the vent air most cases are correctable. correct such as the cylinder exhaust on an automotive fender (Figure 9). • The removed oil is collected Understanding and managing Others are much harder to find such and returned to the gear case equipment inlet air pressure and as oil mist coming from crankcase and temperature, ensuring proper • The gear case is kept in gearbox vents in various compressor negative pressure to allow compressor room ventilation, and drive systems. no outward oil migration managing airborne particulates, caustic gases and oil mists, will have Most conventional crankcase gearbox • This unit appears to be much a direct impact on the reliability and vent systems will have some type of less prone to early fouling and quality of a compressed air system. baffle or filter aglomerator to capture allow excessive crankcase and collect the oil mist coming from pressure build up For more information, please contact the case. This amount will vary by Mr. Nitin G. Shanbhag, Senior Manager, Air Technology Group, drive case pressures. These types of Conclusion Hitachi America, tel: 704-972-9871, aglomerators will range from relatively Ambient conditions cannot be ignored email: [email protected], www.hitachi-america.us/ice/atg crude to very sophisticated but they in order for a compressed air system to all rely heavily on mechanical tapping deliver high quality, reliable, compressed and careful and timely maintenance. air in an energy efficient manner.

HITACHI AMERICA, LTD. Air Technology Group

6901 Northpark Blvd, Suite A Charlotte, NC 28216 Tel: 704.494.3008 [email protected]

Hitachi Industrial Equipment Systems, Co., Ltd. www.hitachi-america.us/ice/atg